QPDF is a C++ library and set of programs that inspect and manipulate the structure of PDF files. It can encrypt and linearize files, expose the internals of a PDF file, and do many other operations useful to end users and PDF developers.

Vipul's Razor is a distributed, collaborative, spam detection and filtering
network. The primary focus of the system is to identify and
disable an email spam before its injection and processing
is complete.

Collectl is a light-weight performance monitoring tool capable of reporting interactively as well as logging to disk. It reports statistics on cpu, disk, infiniband, lustre, memory, network, nfs, process, quadrics, slabs and more in easy to read format.

SpamAssassin for Win32 is a free and powerful anti-spam filter for Windows. Includes a resident daemon for mail servers and a user-friendly personal spam filter that works with any POP3 account and any email client.

CryptoPy is a pure python implmentation of cryptographic algorithms and applications. The algorithms are developed for readability more than speed. The collection now includes IEEE 802.11i specific algorithms that generated the test vectors for 802.11i.

Alicia(Advanced LInux Crash-dump Interactive Analyzer) is a tool that provides the effective environment & interface to analyze Linux crash dump with the power of Perl. New command to edit a dump can be written in perl. Given your script, Got know-how.

Accounting software for small and medium-size businesses, developed for the european style of bookkeeping. EekBoek has both a versatile, scriptable command-line interface (CLI), a GUI, and a programmable API. NL: Boekhouden.

This is a resurrected open source C Interpreter project. The new release includes enhancements that allows the C Interpreter to talk to logic simulation so that it can be used to drive simulation. This project bridges Software and logic simulation.

Statistics modules in Perl Data Language, with a quick-start guide for non-PDL people. They make the PDL shell work like R, but with PDL threading (fast automatic iteration) of procedures including t-test, linear regression, and k-means clustering.

PerlMol is a collection of Perl modules for chemoinformatics and computational chemistry with the philosophy that "simple things should be simple". It should be possible to write one-liners that use this toolkit to do meaningful "molecular munging".